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/* rio.c is a simple stream-oriented I/O abstraction that provides an interface
* to write code that can consume/produce data using different concrete input
* and output devices. For instance the same rdb.c code using the rio abstraction
* can be used to read and write the RDB format using in-memory buffers or files.
*
* A rio object provides the following methods:
* read: read from stream.
* write: write to stream.
* tell: get the current offset.
*
* It is also possible to set a 'checksum' method that is used by rio.c in order
* to compute a checksum of the data written or read, or to query the rio object
* for the current checksum. */
#include "fmacros.h"
#include <string.h>
#include <stdio.h>
#include "rio.h"
#include "util.h"
uint64_t crc64(uint64_t crc, const unsigned char *s, uint64_t l);
/* Returns 1 or 0 for success/failure. */
static size_t rioBufferWrite(rio *r, const void *buf, size_t len) {
r->io.buffer.ptr = sdscatlen(r->io.buffer.ptr,(char*)buf,len);
r->io.buffer.pos += len;
return 1;
}
/* Returns 1 or 0 for success/failure. */
static size_t rioBufferRead(rio *r, void *buf, size_t len) {
if (sdslen(r->io.buffer.ptr)-r->io.buffer.pos < len)
return 0; /* not enough buffer to return len bytes. */
memcpy(buf,r->io.buffer.ptr+r->io.buffer.pos,len);
r->io.buffer.pos += len;
return 1;
}
/* Returns read/write position in buffer. */
static off_t rioBufferTell(rio *r) {
return r->io.buffer.pos;
}
/* Returns 1 or 0 for success/failure. */
static size_t rioFileWrite(rio *r, const void *buf, size_t len) {
return fwrite(buf,len,1,r->io.file.fp);
}
/* Returns 1 or 0 for success/failure. */
static size_t rioFileRead(rio *r, void *buf, size_t len) {
return fread(buf,len,1,r->io.file.fp);
}
/* Returns read/write position in file. */
static off_t rioFileTell(rio *r) {
return ftello(r->io.file.fp);
}
static const rio rioBufferIO = {
rioBufferRead,
rioBufferWrite,
rioBufferTell,
NULL, /* update_checksum */
0, /* current checksum */
{ { NULL, 0 } } /* union for io-specific vars */
};
static const rio rioFileIO = {
rioFileRead,
rioFileWrite,
rioFileTell,
NULL, /* update_checksum */
0, /* current checksum */
{ { NULL, 0 } } /* union for io-specific vars */
};
void rioInitWithFile(rio *r, FILE *fp) {
*r = rioFileIO;
r->io.file.fp = fp;
}
void rioInitWithBuffer(rio *r, sds s) {
*r = rioBufferIO;
r->io.buffer.ptr = s;
r->io.buffer.pos = 0;
}
/* This function can be installed both in memory and file streams when checksum
* computation is needed. */
void rioGenericUpdateChecksum(rio *r, const void *buf, size_t len) {
r->cksum = crc64(r->cksum,buf,len);
}
/* ------------------------------ Higher level interface ---------------------------
* The following higher level functions use lower level rio.c functions to help
* generating the Redis protocol for the Append Only File. */
/* Write multi bulk count in the format: "*<count>\r\n". */
size_t rioWriteBulkCount(rio *r, char prefix, int count) {
char cbuf[128];
int clen;
cbuf[0] = prefix;
clen = 1+ll2string(cbuf+1,sizeof(cbuf)-1,count);
cbuf[clen++] = '\r';
cbuf[clen++] = '\n';
if (rioWrite(r,cbuf,clen) == 0) return 0;
return clen;
}
/* Write binary-safe string in the format: "$<count>\r\n<payload>\r\n". */
size_t rioWriteBulkString(rio *r, const char *buf, size_t len) {
size_t nwritten;
if ((nwritten = rioWriteBulkCount(r,'$',len)) == 0) return 0;
if (len > 0 && rioWrite(r,buf,len) == 0) return 0;
if (rioWrite(r,"\r\n",2) == 0) return 0;
return nwritten+len+2;
}
/* Write a long long value in format: "$<count>\r\n<payload>\r\n". */
size_t rioWriteBulkLongLong(rio *r, long long l) {
char lbuf[32];
unsigned int llen;
llen = ll2string(lbuf,sizeof(lbuf),l);
return rioWriteBulkString(r,lbuf,llen);
}
/* Write a double value in the format: "$<count>\r\n<payload>\r\n" */
size_t rioWriteBulkDouble(rio *r, double d) {
char dbuf[128];
unsigned int dlen;
dlen = snprintf(dbuf,sizeof(dbuf),"%.17g",d);
return rioWriteBulkString(r,dbuf,dlen);
}
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